我们看到一只天鹅在河上滑行。

We saw a ___swan gliding down the river.

在故事中，丑小鸭变成了一只美丽的天鹅。

In the story, the ugly duckling turns into a beautiful ___swan.

天鹅优雅地游过湖面，长脖子弯成弧形。

The ___swan gracefully swam across the lake, its long neck arched.